Shaving block/head worth timing retard? 2.7i/seta

[E30godz]

So I'm piecing together a little 2.7i and going the super eta piston route, which, as i understand will net a 8.5 compression ratio. My question is, will decking the block and/or head within acceptable tolerances net me a large enough compression gain to warrant the retardation in timing that will occur?

If not, what are the alternative means to gain back that timing? I've heard about doing something to the cam gear but I haven't seen many details. I doubt it's as easy as rotating off one tooth on the timing belt (i think that restards or advances 3 degrees?) I suppose it could be remedied with an adjustable timing gear but im trying to avoid any....relatively costly parts.

Input appreciated!

[Mossman]

you can buy adjustable cam gears. I don't know how many teeth there are on the cam gear off the top of my head but for every tooth to be 3* there would have to be a lot more teeth than there are...think aboot it.

[DaveSmed]

If you are off a tooth, its a big difference. Remember, you go by crank degrees of rotation, and the cam turns at half the crank speed so double the actual degree rotation of the cam gear.

Try an adjustable cam gear or some offset dowels/keys (I forget which the M20 uses, I want to say dowel, but I may be thinking Suzuki at the moment)